[As additional resources, links to book reviews and book purchasing information can be found beneath the quotations when this information is available.]
"If you find that your horse consistently doesn't back up straight, make sure the rein pressure is even."
"Moving backwards is always a gesture of submission for a horse."
"Backing up is a powerful and serious correction. Please use it knowingly and sparingly because we do not want to oppress our horses, on the contrary, we want them to trust us and be our friends.
"...if the horse backs well, he understands how to give to pressure."
"An active, rhythmic, and straight reinback is an excellent indicator of the horse's symmetrical development, trust, dexterity, and suppleness."
"Prolonged reinbacks are hard on a horse's hocks and back, so they should be developed gradually."
"A horse with a hind leg well forward under its belly is in a good position to lift and spin its forehand around to that side, so a reinback is sometimes used to set a horse up for quick turns called rollbacks or spins."
"The way to get a horse to stop backing up is to get the horses moving forward again, not to pull on the reins."